Voice command devices may be controlled using audio inputs such vocal instructions or utterances from a user. By removing the need to engage buttons and other modes of touch selection, voice command devices may be operated by a human operator in a hands-free manner. Such a hands-free experience may allow the user to issue commands, while performing other tasks. As more households are equipped with voice command devices, it may be desirable to enhance the security of those voice command devices in order to prevent against threats such as replay attacks.